.main {
  display: flex;
}
.main > div {
  position: relative;
  flex: 1;
  min-height: 200px;
  border: 1px solid red;
}
.main .demo1 .demo {
  position: absolute;
  border-radius: 30px;
  width: 70px;
  height: 70px;
  background: pink;
}
